Heat pump comprising rotary compressor including injection cooling arrangement



Oct. 12, 1965 G. e. COYNE 3,210,953

HEAT PUMP COMPRISING ROTARY COMPRESSOR INCLUDING INJECTION COOLINGARRANGEMENT Filed Sept. 10, 1964 m T N E V m GERARD CoYNE x-us ATTORNEYUnited States Patent HEAT PUMP COMPRISING RGTARY COM- PRESSORINtILUDINtG INJECTION COQLING ARRANGEMENT Gerard G. Coyne, Louisville,Ky., assignor to General Electric Company, a corporation of New YorkFiled Sept. 10, 1964, Ser. No. 395,378 4 Claims. (Cl. 62-324) Thepresent invention relates to heat pumps, otherwise known as reversecycle refrigeration systems, and is more particularly concerned with aheat pump including a rotary compressor and means for supplyingcondensed liquid refrigerant to the compression chamber of thecompressor for cooling purposes during operation of the heat pump oneither the heating or the cooling cycle.

It is common practice in refrigeration systems to employ hermeticallysealed motor compressor units in which the refrigerant compressor andits drive motor are both contained within a hermetically sealed casingand the motor is cooled by the circulating refrigerant. When thehermetic compressor unit is of the high side type, that is one in whichthe compressor withdraws low pressure refrigerant from the system anddischarges high pressure refrigerant into the hermetic casing, it isdesirable to provide some means for cooling the high pressure dischargegas from the compressor before it is passed over the motor. One meansfor cooling the discharge gas before passing it in heat exchangerelationship with the motor comprises injecting a small amount of liquidrefrigerant into the gas being compressed by the compressor. Theinjected liquid refrigerant flashes into gaseous form thereby coolingthe discharge gas sufliciently to provide the desired cooling of themotor by the discharge gas. Compressors including means for injectingliquid refrigerant into the high pressure side of a rotary compressorfor mixture with the gas being compressed therein are disclosed forexample in Patents 3,109,297-Rinehart and 3,105,633-Dellario assigned tothe same assignee as the present invention. In such compressors, liquidrefrigerant from the condenser component of a refrigeration systemincluding the compressor is introduced into the compression chamberthrough an injection port that is opened to the chamber during a periodwhen the pressure of the gas in the chamber is lower than the pressurein the condenser and the pressure differential required for theinjection is obtained by means of a flow restriction between thecondenser and evaporator components of the system.

The present invention is directed to heat pumps including rotarycompressors including injection cooling arrangements and has as itsprincipal object the provision of a heat pump or reverse cyclerefrigeration system including means for assuring the required pressuresat the injection port for introducing liquid refrigerant into thecompression chamber during the operation of the heat pump on either theheating or the cooling cycle.

Further objects and advantages of the invention will become apparent asthe following description proceeds and the features of novelty whichcharacterize the invention will be pointed out with particularity in theclaims annexed to and forming a part of this specification.

In carrying out the objects of the present invention, there is provideda heat pump comprising an indoor heat exchanger and an outdoor heatexchanger connected in a closed refrigerant circuit and a hermeticallysealed motordriven rotary compressor and reversing valve means foreffecting flow of refrigerant through the circuit in either directionwhereby the heat pump can be operated either on the cooling cycle withthe indoor heat exchanger functioning as an evaporator or on a heatingcycle with the indoor heat exchanger functioning as a condenser. Thehermetically sealed compressor includes a rotary compressor FatentedOct. 12, 1965 unit and a drive motor contained in a hermetic casing, thecompressor unit being adapted to discharge high pressure refrigerantinto the casing where it is passed in heat exchange relationship withthe drive motor. For cooling the high pressure refrigerant dischargedfrom the compressor into the casing, the compressor includes a port forinjecting condensed liquid refrigerant into the high pressure side ofthe compression chamber during compression of the gas therein. In orderto provide the required pressure differential to assure the liquidinjection, the circuit includes two series-connected capillary tubesections for restricting the flow of refrigerant from either 7 of theheat exchangers to the other and the liquid refrigerant supply means forsupplying liquid refrigerant to the injection port is connected to therefrigerant circuit at a point between these two capillary tube sectionswhereby during operation of the heat pump on either cycle, therestriction provided by the one of the sections between the connectionpoint and the heat exchanger operating as an evaporator will provide apressure differential sufiicient to introduce liquid refrigerant intothe compression chamber.

For a better understanding of the invention reference may be had to theaccompanying drawing in which:

FIGURE 1 is a somewhat schematic view of a heat pump including thepresent invention; and

FIGURE 2 is a partial plan view of the compressor component of thesystem of FIGURE 1 taken generally along the line 22 of FIGURE 1.

Referring now to FIGURE 1 of the drawing, there is shown a heat pump orreversible refrigeration system comprising an indoor heat exchanger 1and an outdoor heat exchanger 2, the indoor heat exchanger 1 beingadapted to be employed for heating or cooling an enclosure. The two heatexchangers form part of a closed refrigerant circuit including means forwithdrawing refrigerant from either one of the two exchangers anddischarging compressed refrigerant into the other, such means comprisinga compressor 3 and a reversing valve 4. The reversing valve 4 isdesigned to reversibly connect the discharge line 6 and the suction line7 of the compressor to the remaining portion of the system so that thecompressor will withdraw low pressure refrigerant from either the indooror the outdoor heat exchanger and discharge compressed refrigerant intothe other of the two heat exchangers. Thus the outdoor heat exchanger 2functions as a condenser and the indoor heat exchanger 1 as anevaporator when the system is operated on the cooling cycle while theindoor heat exchanger 1 functions as a condenser and the outdoor heatexchanger 2 as an evaporator when the system is operated on the heatingcycle.

For the purpose of controlling or restricting the flow of refrigerantfrom one heat exchanger to the other during normal operation of thesystem on either cycle, there is provided flow restricting meanscomprising series-connected capillary flow restrictors 8 and 9. A bypassline 10 including a check valve 11 is provided for bypassing thecapillary 9. During operation of the heat pump on the heating cycle thecheck valve 11 is closed so that both the capillaries 8 and 9 provideflow restriction between the two heat exchangers. During operation ofthe system on the cooling cycle refrigerant flowing from the heatexchanger 2 bypasses the capillary 9 the only fiow control is providedby the capillary 8, the purpose of this combination of flow restrictingmeans being to provide a greater flow restriction during operation ofthe system on the heating cycle than on the cooling cycle.

The compressor 3 is of the type more fully described in theaforementioned Rinehart Patent 3,109,297 to which reference is made fora detailed description thereof. The compressor comprises a hemeticcasing 12 in which there is contained a rotary compressor 14 including ahousing 3 15 defining an annular compression chamber 16. A rotor 17 iseccentrically rotated within the chamber 16 by means of an eccentric 18forming part of a drive shaft 19 driven by a motor 20. The chamber 16includes a suction or inlet port 22 connected to the suction line 7through which low pressure refrigerant is drawn into the chamber 16during rotation of the rotor 17. A discharge port 23 spaced from theinlet port 22 is provided for discharging high pressure or compressedrefrigerant from the chamber 16 into a discharge chamber 24 from whichit flows through a passage 25 into heat exchange relationship with themotor 20 for ultimate discharge from the casing 12 through the dischargeline 6. A valve 27 controls the flow of discharge gas through thedischarge port 23 and prevents the reverse flow of gas back into thechamber 16.

A movable blade 29 spring biased into engagement with the periphery ofthe rotor 17 and positioned between the suction port 22 and thedischarge port 23 divides the chamber 16 into a low pressure side 30 anda high pressure side 31 whereby during eccentric rotation of the rotor17 within the chamber 16, low pressure refrigerant is drawn into thechamber through the suction port 22 and is discharged through thedischarge port 23 in accordance with the well known operation of arotary compressor of this type.

For the purpose of introducing small amounts of liquid refrigerant intothe high pressure gas discharged from the compressor through the passage25 so as to provide a lower temperature gas stream for cooling the motor20, there is provided an injection port 34 connected by a supply line 35to a point in the refrigerant circuit containing high pressure condensedliquid refrigerant during operation of the system on either the heatingor the cooling cycle. More specifically, the line 35 is connected to thepoint 36 in the circuit between the two capillary flow restrictors 8 and9. Included in the supply passage 35 is a restriction schematicallyillustrated by the capillary 37 in order to limit the amount ofrefrigerant fiow through the passage 35 and thereby prevent shortcircuiting of the evaporator component of the system during operation ofthe injection means.

As is more fully described in the aforementioned Rinehart patent, theinjection port 34 is positioned in an end wall of the chamber 16 on thehigh pressure side of the blade 29, that is adjacent the discharge port23, whereby the injected liquid refrigerant is mixed with the compressedrefrigerant during compression and prior to discharge thereof throughthe valve 27. More specifically, the injection port 34 is positioned sothat it is closed by the rotor 17 except for a short time during thelatter portion of the compression cycle when it is opened to introduceliquid refrigerant into the chamber for mixture with the compressedrefrigerant contained therein. Preferably the injection port 34 isopened at about the same time that the pressure of the gas beingcompressed within the high pressure side 31 of the chamber 16 is about50% that in the case 12 and is closed before the pressure in the highpressure side 31 exceeds that of the case or exceeds the pressure at thepoint 36 between the two capillaries 8 and 9. The injected liquidrefrigerant cools the gas flowing from the compressor into heat exchangewith the motor 20 and thereby provides a lower temperature gas streamfor removing motor heat.

By connecting the supply conduit or line 35 to a point in therefrigerant circuit between the two capillaries, the presence of one orthe other of the two capillaries on the downstream side of the point 36during operation of the heat pump on either of the heating or thecooling cycle assures a pressure condition at the point 36 sufiicient toeffect injection of liquid refrigerant into the compressor chamber. Morespecifically, when the system is operating on the cooling cycle, thecheck valve 11 is open and the point 36 is at substantially the samepressure as the heat exchanger 2 operating as a condenser and the totalflow restriction in the system and hence the pressure differential isprovided by the capillary 8. As a result only high pressure liquidrefrigerant at substantially the same pressure as that existing withinthe heat exchanger 2 flows through the conduit or passage 35 each timethat the injection port 34 is opened. During operation of the heat pumpon the heating cycle, the check valve 11 is closed and both of thecapillaries 8 and 9 provide restriction to the flow of refrigerant fromthe indoor heat exchanger 1 operating as a condenser to the outdoor heatexchanger 2 operating as an evaporator. However, as the capillary 9 isdownstream from the point 36 that is between the point 36 and the heatexchanger 2 operating as an evaporator, the flow restriction provided bythe capillary 9 produces a pressure differential sufficient to causeintroduction of liquid refrigerant into the chamber 16.

While there has been shown and described what is presently considered tobe a preferred embodiment of the present invention, it will be obviousto those skilled in the art that various changes and modifications maybe made therein without departing from the invention and it is thereforeintended by the appended claims to cover all such changes andmodifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A heat pump comprising an indoor heat exchanger and an outdoor heatexchanger connected in a closed refrigerant circuit and a hermeticallysealed motordriven rotary compressor and reversing valve means in saidcircuit for effecting flow of refrigerant through said circuit in eitherdirection whereby said pump may be operated on a cooling cycle with theindoor heat exchanger functioning as an evaporator or on a heating cyclewith the indoor heat exchanger functioning as a condenser,

flow restricting means in said circuit controlling the flow ofrefrigerant from either of said heat exchangers to the other heatexchanger, said flow restricting means comprising two series-connectedcapillary tube sections,

said hermetically sealed compressor comprising a hermetic casing and arotary compressor unit discharging high pressure refrigerant into saidcasing and a drive motor in said casing cooled by said high pressurerefrigerant,

said compressor unit including spaced inlet and discharge ports and ablade slidably extending into said chamber into contact with said rotorbetween said ports thereby to divide said chamber into high and lowpressure sides,

means including an injection port for injecting con densed liquidrefrigerant into the high pressure side of said annular chamber duringcompression of refrigerant gas therein,

and a liquid refrigerant supply means connecting said injection portwith a point in said circuit between said capillary tube sectionswhereby during operation of said heat pump on either cycle, therestriction provided by the one of said sections between said point andthe heat exchanger operating as an evaporator will provide a pressuredifferential sufficient to introduce liquid refrigerant into saidchamher.

2. A heat pump comprising an indoor heat exchanger and an outdoor heatexchanger connected in a closed refrigerant circuit and a hermeticallysealed motor-driven rotary compressor and reversing valve means in saidcircuit for effecting flow of refrigerant through said circuit in eitherdirection whereby said pump may be operated on a cooling cycle with theindoor heat exchanger functioning as an evaporator or on a heating cyclewith the indoor heat exchanger functioning as a condenser,

flow restricting means in said circuit controlling the flow ofrefrigerant from either of said heat exchangers to the other heatexchanger, said flow restricting 3,210,958 6 means comprising twoseries-connected capillary tube said capillary tube sections wherebyduring operation sections and a check valve controlled conduit byof saidheat pump on either cycle the restriction propassing the one of saidsections closest to said outvided by the one of said sections betweensaid point door heat exchanger only during operation of said and theheat exchanger operating as an evaporator heat pump on the coolingcycle, 5 will provide a pressure differential sufiicient to introsardhermetically sealed compressor comprising a herduce liquid refrigerantinto said chamber when said rneticcasing and a rotary compressor unitdischarginjection port is uncovered. hlgh Pressure refrigerant into d Cg d a 4. A heat pump comprising an indoor heat exchanger drive motor insaid casing cooled by said high presand an outdoor heat exchangerconnected in a closed sure refrigerant, 10 refrigerant circuit and ahermetically sealed motor-driven Sald COIHPRSSQI unit lllchldlrlg Pacedlnlet and diS- rotary compressor and reversing valve means in saidcircharge ports and a blade slidably extending into said cuit foreffecting a flow of refrigerant through said circuit chamber intocontact With said rotor between Said in either direction whereby saidpump may be operated ports thereby to divide aid C am r int gh and on acooling cycle with the indoor heat exchanger funclow pressure sldes,tioning as an evaporator or on a heating cycle with the meansll'lcl'lldlpg an lnlectlofl P for inlecting c011 indoor heat exchangerfunctioning as a condenser,

dense? llquld refrigerant into the g Pressure Side flow restrictingmeans in said circuit between said heat Sald annular Chamber duringcompression of exchangers for controlling the flow of refrigerantfrrgerant gas therein, from either of said heat exchangers to the otherheat and a llqllld refrlgel'ant pp y means Connecting Said exchanger,said flow restricting means comprising injection port with a point insaid circuit between said capillary tube sections whereby duringoperation of said heat pump on either cycle, the restriction provided bythe capillary tube section between said point two series-connectedcapillary tube sections and a check valve controlled conduit bypassingthe one of said sections closest to said outdoor heat exchanger onlyduring operation of said heat pump on the cooland the heat exchangeroperating as an evaporator will provide a pressure differentialsufficient to introduce liquid refrigerant into said chamber.

3. A heat pump comprising an indoor heat exchanger and an outdoor heatexchanger connected in a closed refrigerant circuit and a hermeticallysealed motor-driven 3O rotary compressor and reversing valve means insaid circuit for effecting a flow of refrigerant through said circuit ineither direction whereby said pump may be operated on a cooling cyclewith the indoor heat exchanger functioning as an evaporator or on aheating cycle with the indoor heat exchanger functioning as a condenser,

flow restricting means in said circuit between said heat exchangers forcontrolling the flow of refrigerant from either of said heat exchangersto the other heat exchanger, said flow restricting means comprising twoseries-connected capillary tube sections,

said hermetically sealed compressor comprising a hermetic casing and arotary compressor unit and a drive motor in said casing,

said compressor unit including a cylinder having an annular compressionchamber therein and end walls enclosing the ends of said annular chamberand a rotor eccentrically rotatable within said chamber and having aperipheral surface adapted to move progressively into sealing relationwith successive portions of said annular chamber,

said motor including a shaft for driving said rotor within said chamber,

said compressor unit including spaced inlet and discharge ports and ablade slidably extending into said chamber into contact with said rotorbetween said ports thereby to divide said chamber into high and lowpressure sides,

said inlet port being connected to said valve means,

means for conducting hot compressed refrigerant gas from said dischargeport into said hermetic casing, means for conducting high pressurerefrigerant from said casing to said valve means,

means for injecting condensed liquid refrigerant into said annularchamber including a liquid refrigerant injection port on the dischargeport side of said blade and adapted to be covered and uncovered by theend 3,066,497 12/62 Dubberley 62-624 of said rotor during the rotationthereof to compress 3 111 820 11/63 Atchison 5 5 refrigerant in saidchamber,

and a liquid refrigerant supply means connecting said WILLIAM WYE,primary Examiner.

in ection port with a point in said circuit between ing cycle,

said hermetically sealed compressor comprising a hermetic casing and arotary compressor unit and a drive motor in said casing,

said compressor unit including a cylinder having an annular compressionchamber therein and end walls enclosing the ends of said annular chamberand a rotor eccentrically rotatable within said chamber and having aperipheral surface adapted to move progressively into sealing relationwith successive portions of said annular chamber,

said motor including a shaft for driving said rotor within said chamber,

said compressor unit including spaced inlet and discharge ports and ablade slidably extending into said chamber into contact with said rotorbetween said ports thereby to divide said chamber into high and lowpressure sides,

said inlet port being connected to said valve means,

means for conducting hot compressed refrigerant gas from said dischargeport into said hermetic casing, means for conducting high pressurerefrigerant from said casing to said valve means,

means for injecting condensed liquid refrigerant into said annularchamber including a liquid refrigerant injection port on the dischargeport side of said blade and adapted to be covered and uncovered by theend of said rotor during the rotation thereof to compress refrigerant insaid chamber,

and a liquid refrigerant supply means connecting said injection portwith a point in said circuit between said capillary tube sectionswhereby during operation of said heat pump on either cycle therestriction provided by the capillary tube section between said pointand the heat exchanger operating as an evaporator will provide apressure differential sufficient to introduce liquid refrigerant intosaid chamber when said injection port is uncovered.

References Cited by the Examiner UNITED STATES PATENTS

1. A HEAT PUMP COMPRISING AN INDOOR HEAT EXCHANGER AND AN OUTDOOR HEATEXCHANGER CONNECTED IN A CLOSED REFRIGERANT CIRCUIT AND A HERMETICALLYSEALED MOTOR-DRIVEN ROTARY COMPRESSOR AND REVERSING VALVE MEANS IN SAIDCIRCUIT FOR EFFECTING FLOW OF REFRIGERANT THROUGH SAID CIRCUIT IN EITHERDIRECTION WHEREBY SAID PUMP MAY BE OPERATED ON A COOLING CYCLE WITH THEINDOOR HEAT EXCHANGER FUNCTIONING AS AN EVAPORATOR OR ON A HEATING CYCLEWITH THE INDOOR HEAT EXCHANGER FUNCTIONING AS A CONDENSER, FLOWRESTRICTING MEANS IN SAID CIRCUIT CONTROLLING THE FLOW OF REFRIGERANTFROM EITHER OF SAID HEAT EXCHANGERS TO THE OTHER HEAT EXCHANGER, SAIDFLOW RESTRICTING MEANS COMPRISING TWO SERIES-CONNECTED CAPILLARY TUBESECTIONS, SAID HERMETICALLY SEALED COMPRESSOR COMPRISING A HERMETICCASING AND A ROTARY COMPRESSOR UNIT DISCHARGING HIGH PRESSUREREFRIGERANT INTO SAID CASING AND A DRIVE MOTOR IN SAID CASING COOLED BYSAID HIGH PRESSURE REFRIGERANT, SAID COMPRESSOR UNIT INCLUDING SPACEDINLET AND DISCHARGE PORTS AND A BLADE SLIDABLY EXTENDING INTO SAIDCHAMBER INTO CONTACT WITH SAID ROTOR BETWEEN SAID PORTS THEREBY TODIVIDE SAID CHAMBER INTO HIGH AND LOW PRESSURE SIDES, MEANS INCLUDING ANINJECTION PORT FOR INJECTING CONDENSED LIQUID REFRIGERANT INTO THE HIGHPRESSURE SIDE OF SAID ANNULAR CHAMBER DURING COMPRESSION OF REFRIGERANTGAS THEREIN, AND A LIQUID REFRIGERANT SUPPLY MEANS CONNECTING SAIDINJECTION PORT WITH A POINT IN SAID CIRCUIT BETWEEN SAID CAPILLARY TUBESECTINS WHEREBY DURING OPERATION OF SAID HEAT PUMP ON EITHER CYCLE, THERESTRICTION PROVIDED BY THE ONE OF SAID SECTIONS BETWEEN SAID POINT ANDTHE HEAT EXCHANGER OPERATING AS AN EVAPORATOR WILL PROVIDE A PRESSUREDIFFERENTIAL SUFFICIENT TO INTRODUCE LIQUID REFRIGERANT INTO SAIDCHAMBER.